Pulmonary artery (PA) sarcoma is a rare tumor,1 with clinical symptoms and radiological findings that often resemble pulmonary emboli.2 Main PA aneurysm is an uncommon presentation of PA sarcoma. To the best of our knowledge, only 2 cases have been reported,3,4 neither of which was evaluated with 2-deoxy-2-[18F]fluoro-d-glucose (FDG) positron emission tomography (PET)/computed tomography (CT). We report a case of main PA aneurysm due to PA sarcoma without FDG uptake. This is the first autopsy case report of PA sarcoma with main PA aneurysm.
A 38 year-old-man was referred to our hospital for right main PA aneurysm and well-defined multiple nodules in both lungs on chest CT. PET/CT showed FDG uptake in multiple lung nodules, but not in PA aneurysm (Fig. 1A and B). Transthoracic echocardiography and transesophageal echocardiography revealed PA aneurysm compressing left atrium. PA aneurysm due to PA sarcoma with multiple lung metastases was suspected, and the patient underwent thoracoscopic biopsy and pericardial fenestration. PA leiomyosarcoma was diagnosed on the basis of microscopic findings. Surgery was ruled out due to the prognosis and the invasiveness of surgical management. The patient received chemotherapy with pazopanib, which was stopped due to an allergic reaction with rash and fever. He was scheduled for second line chemotherapy, but died suddenly 2 months after the diagnosis. An autopsy was performed with the consent of his family about 26h after death.
PET/CT showed FDG uptake in multiple lung nodules (A), but not in PA aneurysm (B). The thin arrow indicates PA aneurysm (B). Macroscopic findings from the specimen obtained by autopsy revealed PA leiomyosarcoma with cystic degeneration (C). PA, pulmonary artery; LA, left atrium; RA, right atrium.
The autopsy revealed main PA leiomyosarcoma with cystic degeneration (Fig. 1C) and multiple lung and myocardial metastasis. A large amount of blood was found in left thoracic cavity. Pathological findings were consistent with PA leiomyosarcoma with ruptured PA aneurysm. It was speculated that the cause of death was rupture of PA aneurysm.
In general, PA sarcoma shows FDG uptake.2 In this case, PET-CT showed FDG accumulation in multiple lung metastases, but not in pulmonary artery aneurysm. This is because the wall of the aneurysm is too thin for FDG-PET to show FDG uptake. Because of false negatives, therefore, it might be difficult to detect primary pulmonary artery sarcoma with FDG-PET in the presence of an aneurysm.
Two out of 3 patients with main PA aneurysm due to PA sarcoma (2 cases3,4 have been reported in addition to the present case) experienced rupture of main PA aneurysm. Rupture of PA aneurysm is rare because of low pressure of PA.5 But PA aneurysm due to PA sarcoma might be fragile and have a higher risk of rupture than main PA aneurysm due to other diseases.
In conclusion, it might be difficult to detect primary lesion of PA sarcoma with FDG-PET in the presence of an aneurysm. More cases are needed to determine the clinical feature of PA sarcoma with main PA aneurysm.
We would like to thank Dr. Yoshiaki Inayama from the Department of Pathology, Yokohama City University Medical Center for pathological advice, and Dr. Zenko Nagashima from the Department of Cardiology, Yokosuka City Hospital for cardiological advice.
Please cite this article as: Watanabe K, Shinkai M, Kaneko T. Autopsia de un sarcoma de arteria pulmonar, que formaba un aneurisma sin captación de FDG. Arch Bronconeumol. 2016;52:535–536.
